Method and deivce for treating one or more substances in a vessel

ABSTRACT

Apparatus for mixing substances of a pulverulent, pasty, granular or liquid nature and drying slurries or sludges comprising a vessel having a mixing screw which rotates about its own axis and also about the axis of the vessel. The driving mechanism which drives the stirring member about the axis of the vessel includes a hydraulic coupling to reduce the likelihood of the occurrence of a fracture in the stirring member and to reduce the capacity of the motor which is necessary to treat substances of comparatively high viscosity.

United States Patent [56] References Cited UNITED STATES PATENTS 4/1958 Nauta.... 11/1963 Nauta....

[72] Inventor ConstanlJohan Nauta Overveen, Netherlands 747,727

2,831,663 3,109,633 3,450,390 6/1969 Nauta.......................

[21} Appl. N01

22 Filed July 25, 1968 [45] Patented Jan. 19, 1971 Nautamix Patent A. G. Zug, Switzerland a Swiss Company July 27, 1967 Netherlands 67/10,365

[73] Assignee Primary ExaminerRobert W. Jenkins Attorney-Arnold Robinson Priority ABSTRACT: Apparatus for mixing substances of a pulverulent pasty, granular or liquid nature and drying slurries or sludges comprising a vessel having a mixing screw which rotates about its own axis and also about the axis of the vessel. The driving mechanism which drives the stirring member [54] METHOD AND DEVICE FOR TREATING ONE OR MORE SUBSTANCES IN A VESSEL 5 Claims, 1 Drawing Fig.

about the axis of the vessel includes a hydraulic coupling to reduce the likelihood of the occurrence of a fracture in the stirring member and to reduce the capacity of the motor 259/1 1 l, which is necessary to treat substances of comparatively high viscosity.

8 1m H7 90-. 51 20 B Field I 1.1] 2 0 555 [rll METHOD AND DEVICE FOR TREATING ONE OR MORE SUBSTANCES IN A VESSEL BACKGROUND OF THE INVENTION One form of apparatus which is used to perform various treatments on a variety of substances has a vessel in which a stirring member revolves about the vertical axis of the vessel and also about its own axis. Such apparatus is often used to mix pulverulent, pasty, granular and/or liquid substances. It is also used for drying slurries or sludges.

Such an apparatus is not without several disadvantages. For one, in order to allow the apparatus to be used to treat substances which differ greatly in viscosity, the driving motors have to be large enough to supply enough power to treat the substance offering the greatest resistance to the motion of the stirring member. This means that when substances having lower resistances are treated, the driving motors are not being used at full efficiency.

Another disadvantage found in such apparatus is that the stirring member is often damaged or even broken when driven through substances which offer much resistance to the motion of the stirring member.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved apparatus and method for overcoming the disadvantages found in the prior art, such as those set forth above. In accordance with this invention, means are provided for reducing the speed of rotation of the stirring member about the vertical axis of the associated vessel when driven through a substance offering a high resistance to the rotation but allowing the stirring member to rotate about the axis of the vessel at a higher speed when the substance being treated offers comaratively little resistance.

BRIEF DESCRIPTION OF THE DRAWING The drawing shows a side view, partly in section, of an apparatus made in accordance with the present invention.

DETAILED DESCRIPTION OF THE DRAWING The drawing shows a mixing vessel 1 of inverted frustoconical shape having a sidewall 2 which has at its lower end an annular flange 3 to which is secured a bottom 4. Provided in the bottom 4 is a discharge aperture 5 and a slide 6 slideably mounted in guides 7 which are secured to the bottom surface of the bottom 4. The slide 6 has an aperture so that is can be slid to selectively close or open the vessel 1 at the discharge aperture 5.

The upper end of the wall 2 has an annular flange 8 which on one side of the vessel has a broadened portion 9 which is, reinforced by struts 10. Secured to the flange 8 is a suppoi-t' plate 11 which bridges the area defined by the flange 8.

A mixing screw is positioned within the mixing vessel 1 and has a hollow lower end 13 into which extends a bearing pin 14 mounted on the bottom 4 of the mixing vessel 1. The mixing screw 12 has a shaft 15 having at its upper end a pin 17 which projects into a drive arm 16. Mounted on the pin 17 is a bevel gear 18 which meshes with a bevel gear 19 which is fixedly secured at the outer end of a shaft 20. The shaft 20 is rotatably supported in a bearing 21 inside of the drive arm 16. A bevel gear 22 is fixed to the inner end of the shaft 20 and meshes with a bevel gear 23 which is fixed secured to the lower end of a vertically extending shaft 24. The shaft 24 is supported rotatably in a hollow head portion 25 of the drive arm 16. The upper end 26 of the shaft 24 projects upwardly beyond the hollow head portion 25 to accommodate a bevel gear 27 which is secured to the shaft 24 to be driven by a gear 28 which is fixed to the drive shaft 29 of an electric motor 30 which is supported on the support plate 11. It is preferred that the electric motor 30 has a comparatively low speed of rotation.

It should be apparent that the electric motor 30 will cause the mixing screw 12 to rotate at a constant rotation speed about its longitudinal axis. The rotational speed of the electric motor 30 can be reduced considerably by a proper selection of the size of the several bevel gears. Alternatively, a reduction box could be interposed between the motor 30 and the bevel gear 28 to reduce the motor speed.

The head portion 25 of the drive arm 16 is rotatably supported in a bearing ring 31 secured in the rim of an aperture in the support plate 11. A wonn wheel 33 is fixed on a cover plate 32 of the head 25. The worm wheel 33 is driven by a worm shaft 34 which is actually the drive shaft of a reduction gear box 35. The input shaft 36 of the reduction gear box is connected to a driven'member 37 of a hydraulic coupling arrangement 38 which also has an impeller 39. The impeller 39 is driven by an electric motor 40 which is supported on the front plate 11.

It is obvious that the electric motor 40 will cause the mixing screw 12 to revolve about the vertical axis of the mixing vessel 1 at a rotational speed only a fraction of that of the motor 40.

It would be possible to omit the motor 30 by using the motor 40 to drive the bevel gear 27 and thus rotate the mixing screw 12 about its own axis. One way to do this is shown in dotted lines in the drawing. A gear wheel 41 secured to the drive shaft of the motor 40 between that motor and the hydraulic coupling arrangement 38 meshes with a gear 42 secured on a shaft 43 rotatably supported in a bearing 44'mounted on the cover of the hydraulic coupling arrangement 38. Secured to the other end of the shaft 43 is a bevel gear 45 which meshes with the bevel gear 27 on the shaft 26.

It will be seen from the drawing that the exposed gears are enclosed in a dust box 46 to prevent them from becoming dirty and thus prematurely worn out and/or inefficient.

Typically, the drive arm 16 revolves at about 2 revolutions per minute about the axis of the mixing vessel 1 and the electric motor 40 turns at l rotations per minute. At the motor speed of 1,500 rotations per minute, the hydraulic coupling arrangement 37 will impart only about 1,000 rotations per minute to the shaft 36, the exact speed depending on the resistance offered by the substance being treated. When the drive arm 16 is turning the mixing member 12 through a substance or mixture of substances offering a large degree of re sistance, the drive arm 16 will slow down, perhaps a fraction of one rotation per minute, this change being permitted by the hydraulic coupling arrangement 38. Thus, whenever the resistance offered by the substance or substances being treated is comparatively large, the self-regulating arrangement is in the drive mechanism permits the drive arm 16 to slow down and whenever the resistance is comparatively low the drive arm 16 will speed up. This assures that all of the power available will be used to thereby permit the use of comparatively small driving motors in machines which handle, at times, substances which are of a viscosity which would otherwise require larger motors.

The foregoing describes only a preferred method and apparatus and both can be modified without exceeding the scope of the present invention as defined in the following claims.

I claim:

1. Apparatus for treating a substance comprising a vessel, a stirring member in said vessel having a lower end adjacent to the bottom of said vessel, a drive arm which at its inner end is rotatably secured with said vessel and at its outer end supports the upper end of said stirring member, a drive mechanism comprising means to cause rotation of said stirring member about its longitudinal axis and means to rotate said drive arm and thus revolve the said stirring member about the vertical axis of said vessel, the improvement being that the means for causing said stirring member to revolve about the axis of said vessel has self-regulating means so that when a constant driving torque is available, the rotation speed of said stirring member about the axis of said vessel is a function of the resistance offered to said rotation by said substance.

2. A device according to claim ll wherein said mechanism has two electric motors each having its own reduction gearing, the first motor causing rotation of said stirring member about its longitudinal axis and the second motor causing the revolution of said member about the vertical axis of said vessel the reduction gearing of the second motor comprising a hydraulic coupling arrangement which serves as said self-regulating means.

3. A device according to claim 2, characterized in that the hydraulic coupling arrangement is arranged between said second motor and a reduction gearbox which drives said drive arm. 5

4. A device according to claim 1, wherein said drive mechanism has only one electric motor the driven shaft of said motor being connected to said self-regulating means to cause said stirring member to revolve about the vertical axis of said mixing vessel, and a gear wheel is fixed on the driven shaft of the electric motor in front of saidself-regulating means and meshes with a gear wheel fixed on a shaft of the drive mechanism to cause the stirring member to rotate about its longitudinal axis.

5. A method for treating and mixing a substance of a pulverant, pasty granular or the like nature ina vessel having a vertical axis of symmetry, comprising the steps of introducing the substance to be treated into the vessel, causing a stirring member to rotate about its longitudinal axis and to simultaneously rotate about the vertical axis of symmetry of said vessel, applying a constant driving torque to the input of a speed converter coupling, and applying the output of said speed converter coupling to drive said stirring member at various speeds about the axis of symmetry of said vessel as determined by the resistance offered by the substance in the vessel to the rotation of said stirring member. 

1. Apparatus for treating a substance comprising a vessel, a stirring member in said vessel having a lower end adjacent to the bottom of said vessel, a drive arm which at its inner end is rotatably secured with said vessel and at its outer end supports the upper end of said stirring member, a drive mechanism comprising means to cause rotation of said stirring member about its longitudinal axis and means to rotate said drive arm and thus revolve the said stirring member about the vertical axis of said vessel, the improvement being that the means for causing said stirring member to revolve about the axis of said vessel has self-regulating means so that when a constant driving torque is available, the rotation speed of said stirring member about the axis of said vessel is a function of the resistance offered to said rotation by said substance.
 2. A device according to claim 1 wherein said mechanism has two electric motors each having its own reduction gearing, the first motor causing rotation of said stirring member about its longitudinal axis and the second motor causing the revolution of said member about the vertical axis of said vessel the reduction gearing of the second motor comprising a hydraulic coupling arrangement which serves as said self-regulating means.
 3. A device according to claim 2, characterized in that the hydraulic coupling arrangement is arranged between said second motor and a reduction gearbox which drives said drive arm.
 4. A device according to claim 1, wherein said drive mechanism has only one electric motor the driven shaft of said motor being connected to said self-regulating means to cause said stirring member to revolve about the vertical axis of said mixing vessel, and a gear wheel is fixed on the driven shaft of the electric motor in front of said self-regulating means and meshes with a gear wheel fixed on a shaft of the drive mechanism to cause the stirring member to rotate about its longitudinal axis.
 5. A method for treating and mixing a substance of a pulverant, pasty granular or the like nature in a vessel having a vertical axis of symmetry, comprising the steps of introducing the substance to be treated into the vessel, causing a stirring member to rotate about its longitudinal axis and to simultaneously rotate about the vertical axis of symmetry of said vessel, applying a constant driving torque to the input of a speed converter coupling, and applying the output of said speed converter coupling to drive said stirring member at various speeds about the axis of symmetry of said vessel as determined by the resistance offered by the substance in the vessel to the rotation of said stirring member. 